1. The field of art to which the invention pertains includes the art of hoists and lifts for roadway vehicles.
2. Automotive-type hoists are widely used at gasoline stations, repair garages and the like wherever automotive service is customarily performed on the underside of a roadway vehicle. Such hoists are commercially available from a variety of manufacturers and while the hoists may differ in detail from one manufacturer to another, they generally consist of a superstructure including a bolster or a pair of bolsters to which lifting means such as arms or wheel tracks are attached enabling underlying support of a vehicle. A lift mechanism usually driven either electrically or hydraulically operates to elevate a supported vehicle to proper operating height. Since service personnel freely move about beneath an elevated automobile, it is common and indeed made necessary by many local codes to require a fail safe safety device of sorts to prevent lowering or dropping of the hoist other than when expressly intended. Various latch mechanisms for this purpose are known as disclosed, for example, in U.S. Pat. Nos. 2,059,059; 2,750,004; 2,857,985; 3,706,356; and 3,934,680.
While the mechanisms disclosed by these patents undoubtedly would or have functioned well for the purposes intended, they can by generally characterized as of undue complexity and relatively high cost of manufacture and/or installation. Despite recognition of the foregoing, a more satisfactory solution has not heretofore been known.